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Full text of "Alaskan glacier studies of the National Geographic Society in the Yakutat Bay, Prince William Sound and lower Copper River regions"

GLACIERS OF UNAKWIK INLET AND COLLEGE FIORD         305
until the d6bris carried by the ice had accumulated on the surface, forming the ablation moraine, but also long enough for the growth of a few shrubs and of moss and flowers upon the moraine-covered surface. This vegetation upon the bulb was very sparse, however, indicating that melting had gone on fast enough to interfere with plant growth. If the advance of Vassar Glacier which began in 1910 continues Jong enough, crevasses will doubtless break up the lower bulb, so that the ablation moraine will disappear and the lower end of the glacier be transformed to a white mass similar to Bryn Mawr Glacier, instead of the present dirt-covered terminus.
Wellesley Glacier. Wellesley Glacier is a very symmetrical single, cascading ice tongue about  mile wide (PL CXX). It descends the fiord wall from small tributaries in cirques at elevations of over 4000 feet, reaching the water's edge, but not expanding in a piedmont bulb. It descends from a fine hanging valley (PL CXXV) at an elevation of between 1700 and 1800 feet, the slope below the lip exceeding 28. There are inconspicuous lateral moraines and the suggestion of a weak medial moraine, close to the northern margin.
It is evident that not long ago Wellesley Glacier extended at least f of a mile further than now, having then a form very much like that of Vassar Glacier. In retreating from this more advanced position the glacier has left a narrow barren zone along the north and south margins. The site of the central part of this former bulb is occupied by a moraine-bordered cove with water 21 to 129 feet in depth, into which a spit extends from the south side, marking the site of the former terminal moraine. At the head of this cove Wellesley Glacier ends with a vertical ice cliff, beneath the northern and southern margins of which rock ledges show.
Gilbert speaks of it in 1899 as a cascading glacier which "flows with gentle grade through a mountain trough joining the fiord at right angles and then cascades into the sea, into which it plunges without notable modification of profile." This description and the 1899 photograph of the Wellesley Glacier show that it was then essentially as in 1910, and that there was then as now, a broad terminal and lateral barren zone. Although at the time of our visit there was a very much larger barren zone around the glacier terminus than around any other ice tongue in College Fiord, it was then actively advancing, and the northern and southern margins had partly covered the lateral barren zone previously exposed.
On the north side, part of the glacier margin was bordered by a push moraine from 5 to 8 feet high. The advancing edge was lobate, and parts of the barren zone on the mountain slopes were completely covered. Both the ice and the push moraine were overwhelming alders 6 to 6 years old, and broken ice blocks were rolling down the edge of the glacier.
The southern edge of Wellesley Glacier was also bordered by a new push moraine in which were torn willow and alder bushes, some of them 15 years of age. The edge of the ice did not extend across the barren zone, which contained shrubs 8 years old, so that no trees were being overwhelmed by the advancing glacier, although annual plants of 1910 growth were being overturned and buried. The south barren zone has a morainic topography with linear crevasse deposits, knobs, and basins, the latter occupied by pools.
The barren zone in front of the glacier terminus, including the land portion of the former bulb, has evidently been covered by glacial ice within ten or a dozen years, for
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